I bought 74mm TB from carguts a couple weeks back. $85. They have a 30 day return policy if it doesn't work for you; many used parts are in the bin for a reason. I have had one TB from another supplier which didn't work. It would not let the car idle properly. The one on the car now will occasionally rev at idle up to 1800 rpm. So if you get one, put it on the car as soon as you receive it; if there is a problem return it for another. IT CAN BE FRUSTRATING!!
I'm going to Atlanta tomorrow for a tune on a dyno and hope the idle problem will rectify itself after the "tune". That is wishful thinking; the better part of my brain tells me I will still have the occasional high revs. Time will tell.